Early attempts at haploidentical transplantation were hampered by high rates of graft failure and severe graft versus host disease. Recent advances in graft versus host disease prophylaxis with post transplant high dose cyclophosphamide (Cy) have overcome these barriers to a large degree. Published studies have shown that HLA-haploidentical bone marrow transplant (BMT) after non-myeloablative conditioning and using 2 doses of post-transplantation Cy followed by tacrolimus and mycophenolate mofetil (MMF) is a well-tolerated procedure. However, the major cause of treatment failure in this high-risk population was early relapse. As conditioning intensity has been clearly linked to rates of relapse in multiple diseases, it is postulated that utilizing conditioning with higher anti-tumor potential will lead to a lower relapse rate.